Heretofore, chaff materials have been deployed from moving aircraft by one of the following five methods:
(a) Near instantaneous ejection of a clump(s) of dipoles from a plastic cartridge into the adjacent airstream by pyrotechnic or pneumatic means.
(b) Ejecting the contents of a box of chaff by mechanically tearing open the box in the presence of ram air which is exhausted outside of the aircraft or external store structure.
(c) Releasing dipoles into a ram air environment from between two layers of film of synthetic resin composition. The chaff package is stored under tension in roll form and as the roll is mechanically unwound, the dipoles are released from between the film layers into the ram airstream for ejection into the boundary layer of the aircraft or external store.
(d) Dipoles may be released from a forward-fired rocket in one or more bursts at some distance ahead of the aircraft and at a predetermined interval as applicable. Individua1 bursts occur nearly instantaneously and are pyrotechnically actuated.
(e) Firing a chaff loaded bullet from an on-board gun. Chaff contained in the bullet is conveyed to a point 3,000 to 5,000 feet from the aircraft and released
Regardless of the release method utilized, chaff dipoles tend to stop their forward progress very rapidly when released into the airstream due to their low mass and relatively high drag. For said methods (a) and (b) this results in a small chaff cloud forming well aft of the rapidly moving aircraft. For said method (c) the dipole stream is continuous but it does not reach significant width and height dimensions until it is some distance aft of the aircraft. Forward fired rockets can seed chaff clouds ahead of the aircraft which may grow to significant size by the time the aircraft and chaff cloud share the same radar resolution cell and may therefore be effective. This method is very costly, however, and requires the use of an otherwise valuable external stores station for the rocket launcher pod and delays aircraft evasive maneuvers after launch of the rocket. Said method (c) also normally requires a stores station to carry the payload and dispensing mechanism. Said method (e) releases the chaff too far from the aircraft to be effective.
The predominant method in use for tactical aircraft self protect purposes is the nearly instantaneous ejection of clumps of dipoles into the adjacent airstream in accordance with method (a). The dispensing mechanism for this method takes up a minimum of space and pyrotechnic ejection is reliable and safe. With such a system, approximately one third of a pound of various length chaff dipoles are placed in the aircraft boundary layer in approximately 6 to 8 milliseconds. Dipoles from the ejected clumps peel off layer by layer until all that remains is a saturated cloud of dipoles 1 1/2 to 2 meters in width and height and 10 to 12 meters in length. Initial formation of the cloud takes approximately 200 milliseconds. At aircraft velocities on the order of 800 feet per second, cloud formation takes place well aft of the airplane with a maximum cross section of about four square meters when viewed on a radial run.
This invention provides apparatus for ejecting a similar quantity of dipoles which imparts a vector to the chaff cloud transverse to the aircraft line of flight. This is accomplished by ejecting the dipoles which are encased in a spin stabilized payload disk from an ejection cartridge. As a disk travels it emits dipoles in a substantially continuous manner. By ejecting the spinning disk at an angle with respect to the aircraft line-of-flight (90 degrees for example) and releasing dipoles as it moves outwardly, a significant increase in cloud size is achieved while still in the vicinity of the launching aircraft. Relatively minor modification to existing dispenser systems will permit their use with the rectangular cartridge configuration required for this invention. The self-protect ability of the system is enchanced by the rapid chaff cloud formation and its greater size when viewed on a radial run.
This invention provides apparatus for ejecting a spin stabilized payload disk and for emitting chaff dipoles or other materials from the disk case.
The following patents are cited as the most pertinent prior art of which the applicant is aware.
______________________________________ U.S. Pat. No. Name Date ______________________________________ 3,027,047 F. M. Johnson 3-27-62 3,137,231 F. M. Johnson 6-16-64 3,765,336 R. J. Kulsik 10-16-73 4,178,854 G. H. Schillreff 12-18-79 4,183,302 G. H. Schillreff 1-15-80 ______________________________________
Accordingly, this invention provides (a) an expendable payload disk for the distribution of microwave or optically reflective materials in the near vicinity of an aircraft; (b) a means for ejecting the payload disk from an aircraft; (c) a means for arraying chaff or other materials in a direction containing a significant vector outward from an aircraft line-of-flight; and (d) a means to release chaff dipoles or other type material at a substantially uniform rate for a short period of time upon separation from the aircraft.